Health Check for Backup Files

You can instruct Veeam Backup & Replication to periodically perform a health check for the latest restore point in the backup chain. During the health check, Veeam Backup & Replication performs a CRC check for metadata and a hash check for VM data blocks in the backup file to verify their integrity. The health check helps Veeam Backup & Replication make sure that the restore point is consistent, and you will be able to restore data from this restore point and subsequent restore points.

Note:

Veeam Backup & Replication will pass encryption keys to the regular backup repository or cloud repository, If you perform health check for the encrypted backup files. For more information on encryption, see Data Encryption.

The health check is performed at the beginning of the backup copy interval. Veeam Backup & Replication always verifies only the latest point of the backup chain (or the restore point preceding the latest one if the latest restore point is incomplete). Veeam Backup & Replication performs the health check during the first backup copy interval on the day when the health check operation is scheduled. If another backup copy interval runs on the same day, Veeam Backup & Replication will not perform the health check during this backup copy interval. For example, if several backup copy intervals are scheduled to run on Saturday, and the health check is scheduled on Saturday, the health check will only be performed during the first backup copy interval on Saturday.

To run the health check periodically, you must enable the Perform backup files health check option in the backup copy job settings and define the health check schedule. By default, the health check is performed on the last Friday of every month. You can change the health check schedule and instruct Veeam Backup & Replication to perform it weekly or monthly on specific days.

How Health Check Works

Veeam Backup & Replication performs the health check in the following way:

When Veeam Backup & Replication saves a restore point to the backup repository, it calculates CRC values for backup metadata and hash values for data blocks of VM disk in the backup file and saves these values in the metadata of the backup file, together with VM data.

On the day when the health check is scheduled, Veeam Backup & Replication performs the following actions:

At the beginning of the backup copy interval, Veeam Backup & Replication performs the health check for the latest restore point in the backup chain. If the latest restore point in the backup chain is incomplete, Veeam Backup & Replication checks the restore point preceding the latest one.

Veeam Backup & Replication calculates CRC values for backup metadata and hash values for VM disks data blocks in the backup file, and compares them with the CRC and hash values that are already stored in the backup file.

If the health check detects corrupted data blocks, together with data blocks for the new restore point, Veeam Backup & Replication transports valid data blocks for the corrupted restore point. The valid data blocks are stored to the new incremental restore point created with this backup copy interval. As a result, the backup chain gets “fixed”, and you get a possibility to restore data from restore points following the corrupted restore point.

Note:

If the backup copy job uses WAN accelerators, Veeam Backup & Replication attempts to find data blocks in the global cache not to transfer data over the network. For more information, see WAN Acceleration.